The invention relates to an apparatus for removing and disposing of waste of absorption-type refrigerating systems in a manner accounting for requirements of environmental protection.
Starting with the realization that the fluorochlorohydrocarbons used as cooling agents in compressor-operated systems represent a danger for the environment, because they may damage the ozonosphere, refrigerating apparatus are considered as being critically dangerous waste which has to be duly disposed of in controlled manner. Operative evacuation systems, in which the cooling agent is collected and delivered to recycling processes, have been developed for compressor-operated refrigerating systems in which the cooling agent to the greater part is fluorochlorohydrocarbon R12.
Beside compressor-operated refrigerating systems there also exist refrigerating systems of different types which are based on the absorption principle. It is not possible to effect disposal of waste in case of those refrigerating systems using the techniques developed for compressor-operated refrigerating systems. For this reason large numbers of refrigerating apparatus of the absorption type pile up in the dumping grounds of municipal waste disposal and of professional waste disposal enterprises.
In usual absorption-type refrigerating systems, like those which are primarily used in hotels, catering services and for camping appliances, but which are also in addition used in households, the refrigeration process cycle is operated using a mixture from ammonia, water and auxiliary gas. Mainly hydrogen or helium, respectively, is used as pressure-compensating auxiliary gas. For reason of protection against corrosion substantial amounts of Na.sub.2 CrO.sub.4 are added as corrosion inhibitor. In general absorption-type refrigerating apparatus contain about 250 g to 700 g of cooling agent of the following composition:
______________________________________ 32-35 percent by volume 2 percent by volume distilled water ammonia (NH.sub.3) Na.sub.2 CrO.sub.4 (H.sub.2 O) ______________________________________ 80-245 g 5-14 g 165-441 g ______________________________________
and minor amounts by weight of hydrogen or helium. Among these substances ammonia and chromate have to be considered as being detrimental to the environment.
The cooling agent in absorption-type refrigerating apparatus is under increased pressure, usually up to 25 bar. In contrast to the cooling agent contained in a compressor-type apparatus it does not evaporate in case of pressure relief but remains in liquid state in the now open refrigerating system. The ammonia contained in the refrigerating system is eagerly absorbed by the water; at 20.degree. C. 100 ml of water dissolve about 52 g of NH.sub.3. For this reason even in case of leakiness the greater portion of the ammonia can remain in the watery solution of the refrigerating system.
In spite of the fact that ammonia even in natural processes often is created and has a comparatively low toxicity, detrimental effects to health may be caused by larger concentrations, this indicating that a regular disposal and evacutation is required.
As compared thereto, the sodium chromate also contained in the refrigerating system represents a substantially higher risk. Compounds containing chrome, and in particular chromates, are known as being highly carcinogenic, and in case of frequent contact therewith may cause severe allergies. The sodium chromate contained in the refrigerating system of an absorption-type apparatus, however, in case of leakage also remains in the refrigerating apparatus.
Irrespective of the fact whether the refrigerating system in absorption-type apparatus is under pressure or without pressure, it is absolutely necessary to subject the cooling agent contained in the refrigerating system to a regular disposal. Up-to-now there is an absolute lack in suitable plants for such disposal.
In the disposal of the liquid still contained in the refrigerating unit two main problems arise. On one hand it is troublesome to remove the liquid from the refrigerating apparatus; even the application of a vacuum or a multiple perforation of the pipe do not lead to a complete evacuation. On the other hand the content of chromates requires particular attention. When an absorption-type system being under pressure is opened, during pressure relief at first aerosols containing chromate are created, which contain the chromate in tiny little droplets (some .mu.m) which cannot be separated from the waste gas stream without problems. Similar aerosols also come into existence during blowing-out of the refrigerating apparatus with compressed air or another similar agent. Due to the small droplet size and, thus, to the hardly present inertial behaviour of these particles it is neither possible to achieve a sufficient separation by means of simple waste gas deviation and the arrangement of baffle elements. The existing threshold limit value (MAK) of 100 mg/m.sup.3 for Cr cannot be met using traditional methods. In addition, this threshold limit value (MAK) for Cr in may cases is regarded as being too high, so that a further reduction of the value in the future cannot be excluded.